I have a 2013 Shelby Mustang. The book calls for minimum 92 octane. The highest I can find is 90. I don’t think it’s mathematically possible to add enough booster to achieve 92, but it got me wondering; do octane boosters really work? What’s in them anyway?

I would think they work, higher octane means more resistant to combustion, so there are chemicals that will do that. Are you in Denver or some other high altitude place? 90 octane won’t hurt, that’s premium in your area. Anyway, I think premium is ‘recommended’, not ‘required’ for the Shelby, right?

“Premium” is required; 92 is the minimum recommended. Across the country I’ve seen premium range from 90 to 94. There is actually a fairly large difference between 90 and 92 based on what I’ve seen online and adding a can of booster to a tank of gas only raises the octane to something like 90.5, which is why I’m questioning it. I live near sea level, but in a short drive can be 4,000 to 5,000 ft above sea level: Anchorage, AK.
Thanks. Alphonse

@alphonse, do you live in a high altitude area, where the octane numbers on all three fuels show lower numbers than in low altitude areas? If so, that 90 octane fuel you’re buying works as well as 92 octane fuel does at sea level, so it should be fine. You shouldn’t need any octane booster.

From the owner’s manual
"OCTANE RECOMMENDATIONS
Premium unleaded gasoline with an
(R+M)/2 octane rating of 91 or
higher is required. SVT recommends
using unleaded gasoline with octane
rating of 93 or higher for optimal
performance of this vehicle.
Recommended fuel is an important part of the proper maintenance and
optimal performance of this vehicle. The use of gasoline with an octane
rating lower than 91 can lead to severe mechanical damage to your
vehicle, may degrade vehicle performance, and may affect your warranty
coverage."

If you’re using the car for competition purposes, you might want to consider buying a drum of 110 octane racing gas from a company like VP Fuels, installing a hand pump on it, and mix it with your 90 at a oh, 1 to 3 or 4 ratio. My son did that with his turbo Eclipse hot rod (Engine on steroids!!) and it really made a difference.